Tanning



Patented July 15 1924.

KINETE FRANZ HASSLELR, 0F HAMBURG, GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE CHEMICAL FOUNDATION, INC., A CORPORATION OF DELAWARE.

TANNING. 1

No Drawing.

To all whom it may concern:

Be it known that I, FRANZ HAssLER, citizen of the State of Hamburg, Germany, residing at Hamburg, Germany, have invented new and useful Improvements in Tanning, of which the following is a specification.

I have found that I can convert hides into valuable leather by treating them with heat-condensation products of aromatic sulfonic acids which are free from hydroxyl groups other than those occurring in sulfonic acid residues such as can be obtained by simply heating the sulfonic acids. I Condensation products of this kind, especially those derived from aromatic hydrocarbons, have strong tanning properties, even if the sulfonic' acid of the hydrocarbon itself has but weak or no tanning efficiency, as is the case with naphthalene, or toluene, sulfonic acids. As an instance of suitable condensation products which serve for the purpose of the present invention I mention the prod ucts obtained by heating sulfonic acids of naphthalene (alpha or beta), methyl naphthalene, 'anthracene, toluene, or mixed sulfonic acids of toluene and naphthalene, or

of derivatives of hydrocarbons, which are free from hydroxyl groups other than those occurring in sulfonic acid residues, such ascarbazol sulfonic acids, all of which condensation' products are easily soluble in water and strongly precipitate glue solutions.

The following example sets forth an illustrative method by means of which bodies of the above-mentioned type may be prepared, said 'method being presented more in detail in my 00- ending application Serial No. 192,923, filed September 24, 1917.

Equal parts of naphthalene and concentrated sulphuric acid are heated for about 8 hours 'at 130 C. The temperature is then raised to 170 or 180 (3., and the heating is continued until, upon diluting the reaction mixture with water, complete solution of the reaction products takes place. I I

The product, when cold, is a solid, glasslike mass, which is readily soluble in water and capable, in acid solution, of precipitating gelatine or glue from solutions of the same. I

The process of tanning with the aid of the aforesaid sulfonic acids can be carried out in the usual wayflout attention is to be Application filed September 24, 1917. Serial No. 192,925.

called to the fact that the said substances have a strongly acid character and I prefer to employ them in a nearly neutralized condition and to keep the bath in a moderate acid state by adding, if required, small quantities of an acid. The said substances can also be employed together with naturah tanning materials; In most cases a very; fair leather is produced and even if dark colored natural tanning materials are employed, the leather can often be cleared up by simultaneously or afterwards treating with the aforesaid sulfonic acids. Thus, the heat-condensation product derived from naphthalene sulfonio acids produces a white, or but slightly colored leather, whilst the condensation product obtained by heating anthracene sulfonic acid tans hides while simultaneously producing a thoroughly dyed full black shade.

Hides, skins and the like may be tanned with the products hereinbefore mentioned in the following manner:

Take for example 100 lbs. of hides, skins and the like which have been limed and hated, place said hides in a drum and treat at ordinary temperature with a slight: ly acid aqueous solution of a density of about 30 B. of a condensation product obtained as above outlined, such as a condensation product of a naphthalene sulfonic acid and maintain the acidity of the bath by additions of small amounts of dilute sulfuric acid. After about six to eight days, the tanning is complete, whereupon the hides are removed and dried, subsequent to which they may, if so desired, be greased and finished in the usual manner.

Having now fully described my invention, what I claim is:

1. The process of tanning hide which consists in treating the hides with a slightly acid aqueous solution containing a watersoluble glue-precipitating heat-condensation product of an aromatic sulfonic acid, 100

said heat condensation product being free from methylene groups and free from hydroxyl groups other than those occurring in sulfonic acid residues.

2. The process of tanning hides which sation product of a sulfonic acid of an aromatic hydrocarbon, said heat-condensation product being free from methylene groups and free from hydroxyl groups other than those occurring in sulfonic acid residues.

3. The process of tanning hides which consists intreating the hides with a slightly acid aqueous solution containing a watersoluble glue-precipitating heat-condensation product of naphthalene sulfonic acid, said heat-condensation product being free from methylene groups and free from hydroxyl groups other than those occurring in sulonic acid residues. 4 4. The process of tanning hides Which consists in treating the hides With a slightly acid acqueous solution containing a water-soluble glue-preclpitating heat-condensation product of naphthalene sulfonic acid,

said heat-condensation product being free from methylene groups and free from hydroxyl groups other than those occurring in sulfonic acid residues, and said product being obtained by treating naphthalene with concentrated sulfuric acid at 130 C. for 8' hours, raising the temperature to 170 "l80 (l, and heating until the prod-- uct is completely soluble in Water.

In testimony whereof I have hereunto 'c h a. se my an FRANZ HASSLER. 

